The report reveals that the global population of the unaffiliated is 1.1 billion people (16%), or about 1 in 6. As the New York Times explains (emphasis mine):

Something that may surprise a lot of people,” said Conrad Hackett, a primary researcher on the report, “is that the third-largest religious group, after Christians and Muslims, is the religiously unaffiliated. There may have been some guesses floating out there before, but this is the first time there are numbers based on survey data analyzed in a rigorous and scientific way.

Since this data is from 2010, religious demographics will have changed since then. Indeed, more recent Pew surveys indicate that U.S. religious non-affiliation has increased from 16.4% in 2010 to 19.6% in 2012.

This data is should be welcome news for us atheists, agnostics, and the religiously unaffiliated. It shows us the size and strength in numbers some of us may not have been aware existed. Perhaps most importantly, this data shows that we are not alone.